This submission was on the front page of HN yesterday (Show HN: How random are you?):

https://news.ycombinator.com/item?id=50074909

The top comment:

> This is a nice spin on the Aaronson oracle:

> In a class I taught at Berkeley, I did an experiment where I wrote a simple little program that would let people type either “f” or “d” and would predict which key they were going to push next

And today we have a web app of this that seems fully generated by Claude.